BACKGROUND OF THE INVENTION
Field of the Invention
[0001] The present invention relates to a damper valve provided in a hydraulic circuit between
a hydraulic source and a hydraulic actuator, and a hydraulic power steering apparatus
using the same. Description of Related Arts
[0002] Provided as a damper valve is a damper valve having a cylindrical casing, a cylindrical
partition member for partitioning the casing into two chambers, a communication hole
for communicating both end surfaces of the partition member with each other, a valve
seat provided on one of the end surfaces of the partition member, a valve plate opposed
to the valve seat for covering the communication hole, and a spring for urging the
valve plate toward the one end surface of the partition member.
[0004] However, the valve seat and the valve plate are brought into plane contact with each
other, so that oil film cutting easily occurs. Consequently, it is difficult to reliably
prevent the valve plate from being affixed to the valve seat. As a result, a steering
feeling is liable to be bad.
[0005] Document
FR 1 537 110 A discloses a one-way valve having a main plate with bores and an elastically deformable
valve plate. The valve plate is conically covering the main plate and is affixed to
the main plate by a bolt and nut arrangement, wherein a circular portion of the valve
plate is arranged at a distance from a corresponding central portion of the main plate.
[0006] Therefore, an object of the present invention is to provide a damper valve capable
of effectively preventing a valve plate from being affixed to a valve seat and being
not easily separated therefrom, and a hydraulic power steering apparatus using the
same.
The above object is achieved by a damper valve of claim 1.
[0007] According to the present invention, a damper valve comprises a casing having a first
chamber, a second chamber, and a partition wall for separating the first chamber and
the second chamber from each other.
The damper valve comprises a supply path for supplying to the second chamber hydraulic
oil in the first chamber, a return path for returning to the first chamber the hydraulic
oil in the second chamber, a check valve provided in the supply path for regulating
the circulation of the hydraulic oil from the second chamber to the first chamber,
a valve seat provided in the partition wall and facing the first chamber. The damper
valve also comprises an annular valve plate which is elastically deformable, accommodated
in the first chamber and opposed to the valve seat and an urging member for urging
a predetermined portion of the valve plate toward the valve seat. The supply path
comprises a penetration path that penetrates the partition wall along a predetermined
axis. The return path comprises a communication path that communicates the first chamber
and the second chamber with each other by penetrating the partition wall. The communication
path has an opening formed in the valve seat. Either one of the valve seat and the
valve plate is formed into a conical tapered shape centered around the predetermined
axis, so that when either of an outer edge or an inner edge of the valve plate is
abutted against the valve seat, an annular oil chamber is formed between the valve
seat and the valve plate and the opening in the communication path communicates with
the annular oil chamber.
[0008] According to the present invention, an elasticity restoring force of the valve plate
is exerted in the direction in which surface contact (all over abutment) between the
valve plate and the valve seat is restrained, thereby making it possible to effectively
prevent the valve plate from being affixed to the valve seat and being not easily
separated therefrom. It is easy to form either one of the valve seat and the valve
plate into a conical tapered shape, thereby making it possible to make manufacturing
costs lower.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009]
Fig. 1 is a schematic view of a hydraulic power steering apparatus according to a
first embodiment of the present invention;
Fig. 2 is a cross-sectional view of a damper valve according to the first embodiment
of the present invention;
Fig. 3 is a cross-sectional view of a principal part in a state where the damper valve
shown in Fig. 2 is closed;
Fig. 4 is a cross-sectional view in a state where a valve plate shown in Fig. 3 is
elastically deformed;
Fig. 5 is a cross-sectional view in a state where the valve plate shown in Fig. 3
is opened wider than in the state shown in Fig. 4;
Fig. 6 is a cross-sectional view of a principal part of a damper valve according to
a second embodiment of the present invention;
Fig. 7 is a cross-sectional view of a principal part in a state where a damper valve
according to a third embodiment of the present invention is closed;
Fig. 8 is a cross-sectional view in a state where a valve plate shown in Fig. 7 is
elastically deformed;
Fig. 9 is a cross-sectional view in a state where the valve plate shown in Fig. 7
is opened wider than in the state shown in Fig. 8; and
Fig. 10 is a cross-sectional view of a principal part in a state where a damper valve
according to a fourth embodiment of the present invention is closed.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0010] Embodiments of the present invention will be described in detail while referring
to the accompanying drawings.
[0011] In the present embodiment, description is made in conformity with a hydraulic power
steering apparatus comprising a hydraulic cylinder as a hydraulic actuator. As the
hydraulic actuator in the hydraulic power steering apparatus, a hydraulic motor may
be used.
[0012] Fig. 1 is a schematic view of a hydraulic power steering apparatus according to a
first embodiment of the present invention.
[0013] Referring to Fig. 1, in a hydraulic power steering apparatus 100, an input shaft
102 connected to a steering wheel 101, a pinion 103 rotated as the input shaft 102
is rotated, a rack shaft 104 meshed with the pinion 103, a housing 105 covering the
rack shaft 104, a hydraulic cylinder 106 serving as a hydraulic actuator provided
inside the housing 105, a hydraulic pump 107 serving as a hydraulic source for supplying
hydraulic oil to the hydraulic cylinder 106, and a hydraulic control valve 108 interlocked
with the steering wheel 101 for controlling supply and discharge of hydraulic oil
to and from the hydraulic cylinder 106 constitute a principal part.
[0014] Both ends of the rack shaft 104 respectively project from openings 105a and 105b
at both ends of the housing 105, and ball joints 109 and 110 are respectively integrated
with their projecting ends. Tie rods 111 and 112 are respectively mounted on the ball
joints 109 and 110, and the both ends of the rack shaft 104 are connected to a steerable
wheel (not shown) through the tie rods 111 and 112. By a rotation operation of the
steering wheel 101, therefore, the pinion 103 is rotated through the input shaft 102,
and the rack shaft 104 is moved in an axial direction (along the vehicle width), thereby
allowing a vehicle to be steered.
[0015] The hydraulic cylinder 106 has a cylinder tube 106a composed of a part of the housing
105, a piston rod 106b composed of the rack shaft 104, and a piston 106c integrated
with the rack shaft 104. Spaces which are opposite to each other with the piston 106c
are respectively constructed as a first oil chamber 106d and a second oil chamber
106e. A first input port 106f communicating with the first oil chamber 106d and a
second input port 106g communicating with the second oil chamber 106e are formed in
the cylinder tube 106a.
[0016] The hydraulic control valve 108 is composed of a rotary valve, and an input port
108b, a return port 108c, a first output port 108d, and a second output port 108e
are respectively formed so as to project from the valve housing 108a. The input port
108b is connected to an output port 107a on the hydraulic pump 107 through a first
hydraulic pipe 113, and the return port 108c is connected to a reserving oil tank
117 through a second hydraulic pipe 114. The first output port 108d is connected to
the first oil chamber 106d in the hydraulic cylinder 106 through a third hydraulic
pipe 115 serving as a connection path, and the second output port 108e is connected
to the second oil chamber 106e in the hydraulic cylinder 106 through a fourth hydraulic
pipe 116 serving as a connection path.
[0017] The hydraulic control valve 108 supplies steering force assisting hydraulic oil from
the hydraulic pump 107 to either one of the first oil chamber 106d and the second
oil chamber 106e depending on a steering direction and a steering resistance and at
the same time, returns the hydraulic oil to the oil tank 117 from the other oil chamber.
Consequently, the hydraulic cylinder 106 outputs a steering assist force.
[0018] In this type of hydraulic power steering apparatus, there may occur a so-called shimmy
phenomenon that the steerable wheel is excessively vibrated during travel due to the
precision of a steering system part, for example, and the vibration is transmitted
to a steering wheel through a piston rod (a rack shaft) in a hydraulic cylinder, for
example. In order to restrain the shimmy effect, a damper valve 18 is mounted on each
of an end 115a serving as a predetermined portion of the third hydraulic pipe 115
serving as a hydraulic circuit and an end 116a serving as a predetermined portion
of the fourth hydraulic pipe 116.
[0019] Specifically, the third hydraulic pipe 115 comprises a metal pipe, and the metal
pipe is connected to the first input port 106f in the hydraulic cylinder 106 through
the damper valve 18. The fourth hydraulic pipe 116 comprises a metal pipe, and the
metal pipe is connected to the second input port 106g in the hydraulic cylinder 106
through the damper valve 18.
[0020] Each of the damper valves 18 has a function serving as a check valve that allows
flow of hydraulic oil from the hydraulic control valve 108 to the hydraulic cylinder
106 and a function serving as a throttling check valve that allows flow of hydraulic
oil in a direction opposite to the flow of hydraulic oil from the hydraulic control
valve 108 to the hydraulic cylinder 106 with a predetermined resistance.
[0021] The damper valve 18 provided in the third hydraulic pipe 115 and the damper valve
18 provided in the fourth hydraulic pipe 116 are constructed similarly to each other.
Description is now made in conformity with the damper valve 18 provided in the third
hydraulic pipe 115.
[0022] Fig. 2 is a cross-sectional view of the damper valve 18 according to the first embodiment
of the present invention.
[0023] Referring to Fig. 2, a supply path F1 for supplying hydraulic oil to the hydraulic
cylinder 106 and a return path F2 for causing the hydraulic oil to flow out of the
hydraulic cylinder 106 are defined inside the damper valve 18. The supply path F1
and the return path F2 are separated from each other, each of the paths allows only
the circulation of hydraulic oil in the corresponding one direction, and their both
ends communicate with each other. The supply path F1 is provided with a first valve
19 having the function of the check valve (also referred to as a check valve) 19.
Further, the return path F2 is provided with a second valve 20 having the function
of the drawing check valve.
[0024] Specifically, the damper valve 18 comprises a hollow casing 21, a partition wall
23 for partitioning the casing 21 into a first chamber C1 and a second chamber C2,
a check valve 19 serving as the first valve provided inside the partition wall 23,
a valve plate 25 for composing the second valve 20, and a coil spring 24 serving as
an urging member for urging the valve plate 25 through a holding member 22.
[0025] The second valve 20 has a valve seat 26 provided on the partition wall 23 and facing
the first chamber C1, and the above-mentioned valve plate 25 opposed to the valve
seat 26.
[0026] In the present embodiment, when the valve seat 26 is formed into a conical tapered
surface, and the second valve 20 is brought into a closed state, the valve plate 25
in a plane-like annular disk shape is brought into line contact with the valve seat
26. Consequently, it is possible to prevent the valve plate 25 from being affixed
to the valve seat 26. As a result, the conventional problem, that is, that when a
valve plate is affixed to a valve seat, a driver feels a predetermined load in steering
until the valve plate is separated from the valve seat may occur. However, such a
problem is solved, thereby a steering feeling is improved.
[0027] The casing 21 has a flare pipe 21a, a first connector 21b connected to the flare
pipe 21a, and a second connector 21c whose front end is screwed into the first connector
21b. The partition wall 23 is integrally formed at one end inside the first connector
21b. The casing 21 has a hollow shape as a whole by the flare pipe 21a, the first
connector 21b, and the second connector 21c. The casing 21 has the first chamber C1
and the second chamber C2 that are separated from each other by the partition wall
23, a first port P1 communicating with the first chamber C1, and a second port P2
communicating with the second chamber C2.
[0028] Referring to Figs. 1 and 2, the first port P1 is connected to a metal pipe in a third
hydraulic pipe 115 serving as a portion nearer to the hydraulic pump 107 than to the
first port P1 in the hydraulic circuit. The second port P2 is connected to the first
input port 106f on the hydraulic cylinder 106 serving as a portion nearer the hydraulic
cylinder 106 than to the second port P2 in the hydraulic circuit. The first chamber
C1 communicates with the hydraulic control valve 108 through the first port P1 and
the metal pipe in the third hydraulic pipe 115 in this order. The second chamber C2
communicates with the first oil chamber 106d in the hydraulic cylinder 106 through
the second port P2.
[0029] Referring to Fig. 2, the partition wall 23 has the valve seat 26 composed of an annular
end surface provided at one end to face the first chamber C1, and an annular end surface
27 arranged at the other end to face the second chamber C2 in axial directions X1
and X2. Here, the axial directions X1 and X2 are directions in which an axis 23e of
a penetration path 23c in the partition wall 23 extends, the axial direction X1 being
a direction from the first chamber C1 to the second chamber C2, and the axial direction
X2 being a direction from the second chamber C2 to the first chamber C1.
[0030] The partition wall 23 has a plurality of communication paths 23a arranged equally
spaced apart on the circumference centered around the axis 23e and penetrating the
partition wall 23, and the penetration path 23c penetrating the partition wall 23
along the axis 23e. The communication path 23a and the penetration path 23c are respectively
formed so that they can communicate the first chamber C1 and the second chamber C2
with each other. A part of the penetration path 23c constitutes a guide section facing
the first chamber C1 for guiding the holding member 22, and another part of the penetration
path 23c constitutes a holding section facing the second chamber C2 for holding the
check valve 19.
[0031] Fig. 3 is a cross-sectional view of the second valve 20 serving as a principal part
of the damper valve 18 according to the first embodiment of the present invention
and its peripheral part, showing a closed state. Refer to Fig. 3.
[0032] In the present embodiment, the whole valve seat 26 is formed by a conical tapered
surface having the axis 23e of the penetration hole 23c in the partition wall 23 as
its center. The valve seat 26 is recessed in the axial direction X1. The closer a
portion of the valve seat 26 is to an inner peripheral edge thereof, the deeper a
recess of the portion is. In the valve seat 26, a plurality of openings 23b forming
one end of the communication path 23a are arranged equally distributed on the circumference
centered around the axis 23e.
[0033] Returning to Fig. 2, the holding member 22 has a stepped cylindrical shape. The holding
member 22 is arranged concentrically with the axis 23e of the partition wall 23. The
holding member 22 has a small-diameter section 22a having a small outer diameter and
having a cylindrical shape and a large-diameter section 22b having a large outer diameter
and having a cylindrical shape.
[0034] In the small-diameter section 22a and the large-diameter section 22b, penetration
holes 22d serving as their inner parts are respectively formed. The penetration hole
22d allows the circulation of hydraulic oil.
[0035] A diameter of the inner periphery of the large-diameter section 22b is made larger
than the diameter of the inner periphery of the small-diameter section 22a. The coil
spring 24 is arranged inside the large-diameter section 22b. A receiving section that
receives the coil spring 24 is provided on an inner sidewall, nearer to the small-diameter
section 22a, of the large-diameter section 22b.
[0036] A stepped end surface is formed between the outer periphery of the small-diameter
section 22a and the outer periphery of the large-diameter section 22b. A receiving
section 28 for receiving the inner edge 25b of the valve plate 25 is provided in an
inner part in the radial direction of the end surface, and a relief section 22c for
allowing the valve plate 25 to be elastically deformed is provided in an outer part
in the radial direction of the end surface.
[0037] The small-diameter section 22a is fitted in a guide portion of the penetration hole
23c in the partition wall 23, and is movable in the axial directions X1 and X2 relative
to the partition wall 23 along the guide portion.
[0038] An annular spacing S1 is provided between the outer periphery of the large-diameter
section 22b and the inner periphery of the first chamber C1. In addition thereto,
a spacing S2 is provided between an end 22f in the axial direction X2 of the holding
member 22 and the end 21d in the axial direction X1 of the second connector 21c. The
clearances S1 and S2 are respectively set to predetermined amounts, to allow the circulation
of hydraulic oil.
[0039] The supply path F1 comprises the penetration hole 23c in the partition wall 23 and
the penetration hole 22d in the holding member 22 so that hydraulic oil supplied to
the first chamber C1 through the first port P1 can be supplied to the second chamber
C2 through the penetration hole 22d in the holding member 22 and the penetration hole
23c in the partition wall 23 in this order.
[0040] The return path F2 comprises the communication path 23a in the partition wall 23,
the clearance S1, and the clearance S2 so that hydraulic oil returned toward the first
chamber C1 from the second chamber C2 can be circulated to the first chamber C1 through
the communication path 23a and further introduced into the first port P1.
[0041] The check valve 19 allows hydraulic oil to be circulated from the first port P1 to
the second port P2, and regulates a circulation of hydraulic oil in the opposite direction
to the above-mentioned circulation. The check valve 19 is arranged in the supply path
F1 inside the partition wall 23, specifically, in the holding portion of the penetration
hole 23c.
[0042] The check valve 19 comprises a cylindrical case 19a fixed in a press-fitted state
to the holding portion of the penetration hole 23c in the partition wall 23, a movable
valve member 19b arranged inside the case 19a so as to be movable in the axial directions
X1 and X2, a coil spring 19c accommodated inside the case 19a for urging the movable
valve member 19b, and a ring-shaped valve seat member 19d, on which the movable valve
member 19b is seated, attached to the case 19a. The constituent members are assembled
to form an integral unit, thereby constituting the check valve 19.
[0043] Referring to Figs. 1 and 2, the check valve 19 is opened when hydraulic oil is circulated
toward the first oil chamber 106d in the hydraulic cylinder 106 from the hydraulic
control valve 108 during a steering operation, while being closed in other case.
[0044] At normal time when the steering operation is not performed, for example, the check
valve 19 is closed. The movable valve member 19b is brought into close contact with
the valve seat member 19d from the second chamber C2 by an urging force of the coil
spring 19c, to close an opening provided at the center of the valve seat member 19d.
Thus, the check valve 19 brings the penetration hole 23c in the partition wall 23
into a closed state, to prevent a flow of hydraulic oil that returns toward the hydraulic
control valve 108 from the hydraulic cylinder 106.
[0045] When the steering operation is performed as described above, the check valve 19 is
opened. At this time, the movable valve member 19b is separated from the valve seat
member 19d against an urging force of the coil spring 19c by pressure of hydraulic
oil that flows toward the hydraulic cylinder 106 from the hydraulic control valve
108 accompanying to the steering operation. Consequently, the penetration hole 23c
in the partition wall 23 is opened, so that the hydraulic oil from the hydraulic control
valve 108 is supplied to the first oil chamber 106d in the hydraulic cylinder 106
in a direction corresponding to the steering direction of the steering wheel 101 after
successively passing through the supply path F1 and the second port P2 from the first
port P1.
[0046] Referring to Figs. 2 and 3, the valve plate 25 comprises an annular disc spring composed
of a metallic thin plate. The valve plate 25 is formed to have such dimensions that
it can cover the opening 23b facing the first chamber C1 in the communication path
23a. The inner edge 25b of the valve plate 25 is formed so as to have dimensions equal
to the inner diameter of the valve seat 26, and is abutted against a receiving section
28 in the holding member 22 and fitted so as to be movable integrally with the outer
periphery of the small-diameter section 22a in the holding member 22. An outer edge
25a of the valve plate 25 is formed so as to have dimensions substantially equal to
or smaller than the outer diameter of the valve seat 26.
[0047] Fig. 4 is a cross-sectional view in a state where the second valve 20 shown in Fig.
3 is opened. Referring to Figs. 3 and 4, the thickness of the valve plate 25 is set
to such a value that the outer periphery of the valve plate 25 can be elastically
deformed by hydraulic oil with a low flow rate returned through the communication
path 23a . An amount of the elastic deformation gradually increases as the flow rate
of the hydraulic oil increases. Consequently, the communication path 23a can be subtly
opened or closed depending on a flow rate of the hydraulic oil.
[0048] Referring to Fig. 2, the coil spring 24 is composed of a compression spring, to urge
the holding member 22 toward the second chamber C2 along the axial direction X1 by
a predetermined force and press the valve plate 25 toward the valve seat 26 on the
partition wall 23 through the holding member 22. The coil spring 24 is interposed
in a state where it is elastically contracted between the holding member 22 and the
second connector 21c so as to expand and contract depending on a flow rate of the
hydraulic oil that returns along the return path F2.
[0049] The second valve 20 is opened when the hydraulic oil is returned at a flow rate of
not less than the first predetermined flow rate along the return path F2, while being
closed in other cases. For example, when there is no hydraulic oil returned from the
first oil chamber 106d in the hydraulic cylinder 106 to the hydraulic control valve
108, and the flow rate of the hydraulic oil thus returned is very low, the second
valve 20 is closed.
[0050] Referring to Figs. 2 and 3, the valve plate 25 covers the opening 23b at a position
apart from the opening 23b in a state where the second valve 20 is closed. The coil
spring 24 urges the inner edge 25b of the valve plate 25 toward the valve seat 26
in a state where a clearance is provided between the inner edge 25b of the valve plate
25 and the valve seat 26. On the other hand, only the outer edge 25a of the valve
plate 25 is in annular contact with the valve seat 26 substantially in a line contact
state. As a result, an annular oil chamber 70 is formed between the valve plate 25
and the valve seat 26.
[0051] The opening 23b in each of the communication paths 23a is opened to the annular oil
chamber 70, so that hydraulic oil is introduced into the annular oil chamber 70 from
the communication path 23a. Consequently, it is possible to prevent oil film cutting
from occurring in the valve seat 26. As a result, it is possible to effectively prevent
from occurring a so-called affixation phenomenon that the valve plate 25 adheres to
the valve seat 26 not to be easily separated therefrom.
[0052] The inner edge 25b of the valve plate 25 receives an urging force (a leftward force
in Fig. 3) toward the valve seat 26 from the coil spring 24, while the outer edge
25a receives a reaction force (a rightward force in Fig. 3) in the opposite direction
to the urging force from the valve seat 26. An elasticity restoring force is produced
in the valve plate 25 so as to be balanced with the reaction force and the urging
force. The elasticity restoring force is exerted in a direction in which surface contact
between the valve plate 25 and the valve seat 26 is restrained, and it is specifically
exerted so as to separate the inner edge 25b of the valve plate 25 from the valve
seat 26 with the outer edge 25a used as a support.
[0053] Referring to Figs. 1 and 2, when a piston rod 106b in the hydraulic cylinder 106
is vibrated rightward and leftward as the steerable wheel is slightly vibrated, the
second valve 20 is opened a little. That is, a flow of hydraulic oil that returns
from the first oil chamber 106d to the hydraulic control valve 108 is produced by
the vibration at a low flow rate. When the flow rate at this time exceeds the first
predetermined flow rate, the valve plate 25 in the damper valve 18 is elastically
deformed depending on the flow rate so that the pressure of the flow causes the opening
23b to be opened wider as shown in Figs. 3 and 4.
In this case, the return path F2 is throttled by the valve plate 25, so that a damper
effect is exhibited. Therefore, the vibration from the steerable wheel is prevented
from being transmitted to the steering wheel 101 through the piston rod 106b in the
hydraulic cylinder 106. On the other hand, when a driver performs rapid steering,
hydraulic oil returned toward the hydraulic control valve 108 from the first oil chamber
106d in the hydraulic cylinder 106 increases in amount. When a flow rate of the hydraulic
oil thus returned is higher than a second predetermined flow rate which is set to
a higher value than the first predetermined flow rate, the second valve 20 is opened
wide.
[0054] Fig. 5 is a cross-sectional view in a state where the second valve 20 is opened wider
than that in the state shown in Fig. 4. Referring to Figs. 2 and 5, the valve plate
25 is elastically deformed by hydraulic oil returned at a high flow rate so that the
opening 23b is opened wider. Correspondingly, an amount of compression of the coil
spring 24 is relatively increased by a force of hydraulic oil with a high flow rate
urging the valve plate 25. As a result, the valve plate 25, together with the holding
member 22, is moved against an urging force of the coil spring 24 and is greatly separated
from the valve seat 26 in the partition wall 23, to open the opening 23b wider.
[0055] Referring to Figs. 1 and 5, The second valve 20 is opened wide as described above,
so that hydraulic oil from the hydraulic cylinder 106 is smoothly returned to the
hydraulic control valve 108 through the second valve 20 in the damper valve 18. As
a result, a steering assist force is prevented from being lowered so that it is possible
to prevent such a problem from occurring that the steering wheel 101 abnormally increases
in weight.
[0056] Referring to Fig. 2, in the embodiment of the present invention, the valve seat 26
in the partition wall 23 is formed into a conical tapered surface. Consequently, an
elasticity restoring force of the valve plate 25 is exerted in a direction in which
surface contact (solid abutment) between the valve plate 25 and the conical tapered
surface is restrained, thereby making it possible to effectively prevent the valve
plate 25 from being affixed to the valve seat 26 and being not easily separated therefrom.
Further, the conical tapered surface can be formed at lower cost, as compared with
that in case where a recess is formed on its end surface. In order to obtain this
effect, the valve seat 26 may include the conical tapered surface.
[0057] Referring to Fig. 3, the outer edge 25a of the valve plate 25 and the valve seat
26 in the partition wall 23 are substantially brought into line contact, thereby making
it possible to more effectively prevent the valve plate 25 from being affixed to the
valve seat 26 on the partition wall 23 and being not easily separated therefrom. Hydraulic
oil with a low flow rate can be reliably prevented by the outer edge 25a of the valve
plate 25 while maintaining the above-mentioned line contact by utilizing the elasticity
restoring force of the valve plate 25.
[0058] In the hydraulic power steering apparatus 100 (see Fig. 1) comprising the damper
valve 18 according to the present embodiment, an affixation phenomenon between the
valve seat 26 on the partition wall 23 and the valve plate 25 in the damper valve
18 can be prevented from occurring, thereby making it possible to prevent a steering
feeling from degrading.
[0059] In a cross section including the axis 23e, it is preferable that an angle DA that
is an angle formed between the valve seat 26 and the axis 23e and on the side of a
portion where the valve plate 25 exists is an acute angle, thereby making it possible
to obtain the above-mentioned effect by using the plate-shaped valve plate 25. It
is more preferable that the angle DA is set to a value larger than 89.0 degrees. Thus,
the valve seat 26 is similar to a flat shape. Therefore, substantially the same damper
effect as that in a conventional second valve in which both of an end surface and
a valve plate are flat can be obtained, so that practical applications can be easily
made. It is more preferable that the angle DA is set to a value smaller than 89.5
degrees. Thus, the valve seat 26 and the valve plate 25 are reliably brought into
line contact. Further, it is more preferable that the angle DA is set to a value within
a range from 89.0 degrees to 89.5 degrees.
[0060] When the angle DA is set to a small value that is less than 89.0 degrees, a degree
at which the shape of the valve seat 26 is similar to a flat surface is reduced, so
that damper characteristics may differ from those in the conventional example. When
the angle DA is set to a large value exceeding 89.5 degrees, the valve seat 26 and
the flat valve plate 25 may be brought into surface contact so that affixation cannot
be restrained.
[0061] The following modified example can be considered with respect to the present embodiment.
In the following description, points different from those in the above-mentioned embodiment
will be described, and the same constituent elements are assigned the same reference
numerals and hence, the description thereof is not repeated.
[0062] For example, in the first embodiment, it can be also considered that the angle of
inclination DA of a tapered surface is made smaller than 89 degrees, for example.
[0063] Fig. 6 is a cross-sectional view of a second valve 20 serving as a principal part
of a damper valve according to a second embodiment of the present invention and its
peripheral portion of the second valve 20.
[0064] In a damper valve 18 according to the second embodiment, a valve seat 26A in a partition
wall 23 is formed into a conical tapered surface inclined in a direction opposite
to the valve seat 26 in the embodiment shown in Fig. 1, and the above-mentioned angle
DA is an obtuse angle. A receiving section 28A in a holding member 22 is composed
of projections provided radially outward away from an inner edge 25b of a valve plate
25 spaced by a predetermined distance, and the projection has an annular shape centered
around an axis 23e to receive a vicinity of the inner edge 25b of the valve plate
25.
[0065] As shown in Fig. 6, in a state where a second valve 20 is closed, only the inner
edge 25b of the valve plate 25 is abutted against the valve seat 26 in a line contact
state, and the outer edge 25a is separated from the valve seat 26A. Consequently,
an annular oil chamber 70 is formed between the valve plate 25 and the valve seat
26A. An elasticity restoring force of the valve plate 25 is exerted in a direction
in which surface contact (solid abutment) between the valve plate 25 and the conical
tapered surface is restrained. Consequently, it is possible to effectively prevent
the valve plate 25 from being affixed to the valve seat 26A on the partition wall
23 and being not easily separated therefrom.
[0066] In the second embodiment, the valve plate 25 does not completely close an opening
23b, and a small amount of hydraulic oil is freely returned, so that a so-called ON/OFF
feeling of a driver can be suppressed due to rapid return of the hydraulic oil.
[0067] In the first embodiment, only a portion i:n a radial direction of the valve seat
26 that is a portion where the valve seat 26 and the valve plate 25 are abutted against
each other in a line contact state may be formed into a conical tapered surface. The
valve seat 26 may also be formed into a curved shape. It can be said that the valve
seat 26 in this case comprises a lot of conical tapered surfaces that gradually differ
in angle of inclination, and that the conical tapered surfaces form an R shape. Such
a modified example can be also considered regarding the valve seat 26A in the second
embodiment.
[0068] Fig. 7 is a cross-sectional view of a second valve 20 serving as a principal part
of a damper valve according to a third embodiment of the present invention and peripheral
portion of a second valve 20, showing a closed state.
[0069] In a damper valve 18 according to the third embodiment, a valve seat 26B on a partition
wall 23 is formed into a flat annular surface that crosses at right angles to an axis
23e. The second valve 20 has the valve seat 26B and a valve plate 30. The valve plate
30 is composed of a disc spring having a conical shape in an unloaded state, and an
inner edge 30b of the valve plate 30 is arranged in an axial direction X2 away from
an outer edge 30a.
[0070] In a state where the second valve 20 is closed, a predetermined clearance is provided
between the inner edge 30b of the valve plate 30 urged by a coil spring 24 through
a receiving section 28 of a holding member 22 and a valve seat 26. An outer edge 30a
and the valve seat 26 are substantially brought into line contact, so that the valve
plate 30 covers an opening 23b, thereby preventing the circulation of hydraulic oil.
An annular oil chamber 70 is defined between the valve plate 30 and the valve seat
26, and the opening 23b communicates with the annular oil chamber 70.
[0071] The valve plate 30 composed of a disc spring in a conical shape produces an elasticity
restoring force exerting so that the disc spring is returned to the conical shape
when it receives such a force as to make the disc spring flat.
[0072] Fig. 8 is a cross-sectional view in a state where the second valve 20 shown in Fig.
7 is opened. Fig. 9 is a cross-sectional view in a state where the second valve 20
shown in Fig. 7 is opened wider than that in the state shown in Fig. 8.
[0073] When a flow rate of the hydraulic oil to be returned is relatively low, higher than
a first predetermined flow rate and lower than a second predetermined flow rate, as
shown in Fig. 8,a circulation of hydraulic oil is allowed by only elastical deformation
of the valve plate 30. When a flow rate of hydraulic oil to be returned is relatively
high and is higher than the second predetermined flow rate, as shown in Fig. 9, the
valve plate 30 is elastically deformed, and the valve plate 30, together with the
holding member 22, is displaced in an axial direction X2 against an elastic urging
force of the coil spring 24, to allow a circulation of more hydraulic oil.
[0074] In the third embodiment, an elasticity restoring force of the disc spring serving
as the valve plate 30 that returns to a conical shape is thus exerted in a direction
in which surface contact (solid abutment) between the disc spring and the valve seat
26B on the partition wall 23 is restrained, thereby making it possible to effectively
prevent the valve plate 30 from being affixed to the valve seat 26 on the partition
wall 23 and being not easily separated therefrom. Further, oil film cutting can be
prevented from occurring by utilizing the disc spring serving as the valve plate 30,
thereby making it possible to simplify a shape of the valve seat 26B in the partition
wall 23 for preventing oil film cutting. Therefore, the flat valve seat 26B can be
formed at low cost, for example. In order to obtain this effect, the valve seat 30
may comprise a disc spring.
[0075] Even when the outer edge 30a of the valve plate 30 and the valve seat 26B are brought
into line contact, the annular oil chamber 70 can be formed between the valve plate
30 and the valve seat 26B in a portion other than a portion where they are brought
into line contact. As a result, it is possible to more effectively prevent the valve
plate 30 from being affixed to the valve seat 26 on the partition wall 23 and being
not separated therefrom. Hydraulic oil with a low flow rate can be reliably prevented
from being circulated by the outer edge 25a of the valve plate 30 while maintaining
the above-mentioned line contact utilizing the elasticity restoring force of the by
valve plate 30.
[0076] Fig. 10 is a cross-sectional view of a second valve 20 serving as a principal part
of a damper valve according to a fourth embodiment of the present invention and peripheral
portion of the second valve 20, showing a closed state.
[0077] In a damper valve 18 according to the fourth embodiment, the second valve 20 has
a valve seat 26B serving as a valve seat and a valve plate 31. The valve plate 31
comprises a disc spring forming a conical shape in an unloaded state. The valve plate
31 is opposed to the valve seat 26B in an opposite direction to the valve plate 30
in the embodiment shown in Fig. 7. An intermediate portion in a radial direction of
the valve plate 31 is urged by a coil spring 24 through a receiving section 28A in
a holding member 22. In a state where the second valve 20 is closed, the valve plate
31 is urged by the coil spring 24 through the receiving section 28A of the holding
member 22, so that only an inner edge 31b of the valve plate 31 is abutted against
the valve seat 26 in a line contact state, and an outer edge 31a of the valve plate
31 is in close proximity to an inner periphery of a first chamber C1. In this state,
the valve plate 31 covers an opening 23b but does not completely close the opening
23b.
[0078] Also in the fourth embodiment, it is possible to prevent the valve plate 31 from
being affixed to the valve seat 26B in a partition wall 23 and being not easily separated
therefrom, as in the third embodiment. A so-called ON/OFF feeling of a driver can
be suppressed, as in the second embodiment.
[0079] In the third embodiment, it is also considered that only a portion of the valve plate
30 that is a portion abutted against that the valve seat 26B is formed into a disc
spring, and the cross-sectional shape of the disc spring is brought into an R shape.
The same modified example as this can be also considered in the fourth embodiment.
[0080] It is also considered that any one of the valve seats 26 and 26A and their modified
examples and any one of the valve plates 30 and 31 and their modified examples are
combined with each other to constitute the second valve 20.
[0081] In a hydraulic circuit for connecting the first output port 108d in the hydraulic
control valve 108 and the first input port 106f in the hydraulic cylinder 106 as both
ends thereof, a predetermined portion of the hydraulic circuit provided with the damper
valve 18 may be one of the both ends or a portion intermediate therebetween. For example,
the damper valve 18 may be provided inside the first output port 108d in the hydraulic
control valve 108.
[0082] While the invention has been described in detail with respect to specific embodiments
thereof, it will be appreciated that those skilled in the art, upon attaining an understanding
of the forgeoing, may readily conceive of alterations to, variations of, and equivalents
to these embodiments. Accordingly, the scope of the present invention should be assessed
as that of the appended claims.
1. A damper valve (18) comprising:
a casing (21) having a first chamber (C1), a second chamber (C2), and a partition
wall (23) for separating the first chamber (C1) and the second chamber (C2) from each
other;
a supply path (F1) for supplying hydraulic oil in the first chamber (C1) to the second
chamber (C2);
a return path (F2) for returning the hydraulic oil in the second chamber (C2) to the
first chamber (C1);
a check valve (19) provided in the supply path (F1) for regulating circulation of
the hydraulic oil from the second chamber (C2) to the first chamber (C1);
a valve seat (26; 26A; 26B) provided on the partition wall (23) and facing the first
chamber (C1);
an annular valve plate (25; 30; 31), which is elastically deformable, accommodated
in the first chamber (C1) and opposed to the valve seat (26; 26A; 26B); and
an urging member (24) for elastically urging a predetermined portion (25b; 30b; 31b)
of the valve plate (25; 30; 31) toward the valve seat (26; 26A; 26B), wherein
the supply path (F1) comprises a penetration path (23c) that penetrates the partition
wall (23) along a predetermined axis (23e),
the return path (F2) comprises a communication path (23a) that communicates the first
chamber (C1) and the second chamber (C2) with each other by penetrating the partition
wall (23),
the communication path (23a) has an opening (23b) formed on the valve seat (26; 26A;
26B), and
either one of the valve seat (26; 26A; 26B) or the valve plate (25; 30; 31) is formed
into a conical tapered shape centered around the predetermined axis (23e) and the
valve plate (25) produces an elasticity restoring force so as to achieve a balance
between the urging force provided by the urging member (24) and a reaction force by
the valve plate (25), the valve plate (25; 30; 31) being in line contact with the
valve seat (26; 26A; 26B) when keeping the balance between the elastic urging force
provided by the urging member (24) and the elastic reaction force, so that when either
one of an outer edge (25a; 30a; 31a) or an inner edge (25b; 30b; 31b) of the valve
plate (25; 30; 31) is abutted against the valve seat (26; 26A; 26B), an annular oil
chamber (70) is formed between the valve seat (26; 26A; 26B) and the valve plate (25;
30; 31) and the opening (23b) of the communication path (23a) communicates with the
annular oil chamber (70).
2. The damper valve (18) according to claim 1, wherein
when either one of the outer edge (25a; 30a; 31a) or the inner edge (25b; 30b; 31b)
of the valve plate (25; 30; 31) is abutted against the valve seat (26; 26A; 26B),
the other edge is separated from the valve seat (26; 26A; 26B).
3. The damper valve (18) according to claim 1 or 2, wherein
the valve plate (25; 30; 31) comprises an annular disc spring (25; 30; 31).
4. The damper valve (18) according to claim 3, wherein
the disc spring (30; 31) has a conical tapered shape in an unloaded state.
5. The damper valve (18) according to claim 3 or 4, further comprising
a holding member (22) for holding the disc spring (25; 30; 31) so that the disc spring
(25; 30; 31) is movable along the predetermined axis (23e),
the urging member (24) urging the disc spring (25; 30; 31) toward the valve seat (26;
26A; 26B) through the holding member (22).
6. The damper valve (18) according to claim 5, wherein
when an amount of returned hydraulic oil from the opening (23b) of the communication
path (23a) is not less than a predetermined amount, the valve plate (25; 30; 31),
together with the holding member (22), is displaced in a direction away from the valve
seat (26; 26A; 26B) against the urging member (24).
7. The damper valve (18) according to claim 5 or 6, wherein
the holding member (22) has a cylindrical shape, and
the supply path (F1) penetrates the holding member (22).
8. The damper valve (18) according to any of claims 5-7, wherein
the urging member (24) comprises a coil spring (24) centered around the predetermined
axis (23e),
the holding member (22) comprises a small-diameter section (22a) having a relatively
small diameter and a large-diameter section (22b) having a relatively large diameter,
and
the large-diameter section (22b) of the holding member (22) surrounds the coil spring
(24), to guide expansion and contraction of the coil spring (24).
9. The damper valve according to claim 8, wherein
the small-diameter section (22a) of the holding member (22) is fitted in the penetration
path in the supply path (F1) so as to be slidable along the predetermined axis (23e).
10. The damper valve (18) according to claim 8 or 9, wherein
the holding member (22) comprises a receiving section (28; 28A) for receiving the
inner edge (25b; 30b; 31b) of the disc spring (25; 30; 31), and
the receiving section (28; 28A) is formed between the small-diameter section (22a)
and the large-diameter section (22b).
11. The damper valve (18) according to any of claims 1-10, wherein
the check valve (19) is arranged in the penetration path that penetrates the partition
wall (23).
12. A hydraulic power steering apparatus (100) comprising:
a hydraulic source (107);
an oil tank (117);
a hydraulic actuator (106) having a pair of oil chambers (106d, 106e) for producing
a steering assist force;
a control valve (108) for connecting either one of the oil chambers (106d, 106e) in
the hydraulic actuator (106) to the hydraulic source (107) and connecting the other
of the oil chambers (106d, 106e) to the oil tank (117) depending on a steering direction,
a pair of connection paths (115, 116) for connecting the pair of oil chambers (106d,
106e) in the hydraulic actuator (106) to a pair of ports (108d, 108e) in the control
valve (108) respectively; and
a pair of damper valves (18) provided in the pair of connection paths (115, 116) respectively,
each of the damper valves (18) being a damper valve (18) according to any of claims
1-11.
13. The hydraulic power steering apparatus (100) according to claim 12, wherein
the second chamber (C2) in each of the damper valves (18) is connected to the corresponding
oil chamber (106d, 106e) in the hydraulic actuator (106), and
the first chamber (C1) in each of the damper valves (18) is connected to the corresponding
connection path (115, 116).
14. The damper valve according to claim 1, wherein a holding member (25) includes a small-diameter
section (22a) and a large-diameter section (22b),
wherein a stepped end surface is formed between the small-diameter section (22a) and
the large-diameter section (22b), and
wherein a receiving section (28) for receiving the inner edge (25b) of the valve plate
(25) is provided in an inner part in the radial direction of the end surface, and
a relief section (22c) for allowing the valve plate (25) to be elastically deformed,
is provided in an outer part in the radial direction of the end surface.
1. Dämpfungsventil (18) mit:
einem Gehäuse (21), das eine erste Kammer (C1), eine zweite Kammer (C2) und eine Trennwand
(23) zum Trennen der ersten Kammer (C1) und der zweiten Kammer (C2) voneinander aufweist;
einem Zuführweg (F1) zum Zuführen von Hydrauliköl in der ersten Kammer (C1) in die
zweite Kammer (C2);
einem Rückführweg (F2) zum Rückführen des Hydrauliköls in der zweiten Kammer (C2)
in die erste Kammer (C1);
einem Rückschlagventil (19), das in dem Zuführweg (F1) vorgesehen ist, um eine Zirkulation
des Hydrauliköls von der zweiten Kammer (C2) in die erste Kammer (C1) zu regulieren;
einem Ventilsitz (26; 26A; 26B), der in der Trennwand (23) vorgesehen ist und in Richtung
der ersten Kammer (C1) weist;
einer ringförmigen Ventilplatte (25; 30; 31), die elastisch deformierbar, aufgenommen
in der ersten Kammer (C1) und gegenüberliegend dem Ventilsitz (26; 26A; 26B) ist;
und
einem Druckelement (24) zum elastischen Drücken eines vorbestimmten Abschnitts (25b;
30b; 31b) der Ventilplatte (25; 30; 31) in Richtung des Ventilsitzes (26; 26A; 26B),
wobei
der Zuführweg (F1) einen Durchstoßweg (23c) umfasst, der die Trennwand (23) entlang
einer vorbestimmten Achse (23e) durchstößt,
der Rückführweg (F2) einen Verbindungsweg (23a) umfasst, der die erste Kammer (C1)
und die zweite Kammer (C2) miteinander mittels Durchstoßen der Trennwand (23) verbindet,
der Verbindungsweg (23a) eine Öffnung (23b) aufweist, die auf dem Ventilsitz (26;
26A; 26B) gebildet ist, und
entweder der Ventilsitz (26; 26A; 26B) oder die Ventilplatte (25; 30; 31) in eine
konisch verjüngte Form gebildet ist, die um die vorbestimmte Achse (23e) zentriert
ist, und die Ventilplatte (25) eine Elastizitätsrückstellkraft erzeugt, um ein Gleichgewicht
zwischen der durch das Druckelement (24) bereitgestellten Druckkraft und
einer Reaktionskraft durch die Ventilplatte (25) zu erreichen, wobei die Ventilplatte
(25; 30; 31) in Linienkontakt mit dem Ventilsitz (26; 26A; 26B) ist, wenn das Gleichgewicht
zwischen der elastischen Druckkraft, die durch das Druckelement (24) erzeugt ist,
und der elastischen Reaktionskraft erhalten ist, so dass wenn entweder eine Außenkante
(25a; 30a; 31a) oder eine Innenkante (25b; 30b; 31b) der Ventilplatte (25; 30; 31)
an dem Ventilsitz (26; 26A; 26B) anliegt, eine ringförmige Ölkammer (70) zwischen
dem Ventilsitz (26; 26A; 26B) und der Ventilplatte (25; 30; 31) gebildet ist und die
Öffnung (23b) des Verbindungswegs (23a) in Verbindung mit der ringförmigen Ölkammer
(70) steht.
2. Dämpfungsventil (18) nach Anspruch 1, wobei,
wenn entweder die Außenkante (25a; 30a; 31a) oder die Innenkante (25b; 30b; 31b) der
Ventilplatte (25; 30; 31) an dem Ventilsitz (26; 26A; 26B) anliegt, die andere Kante
von dem Ventilsitz (26; 26A; 26B) getrennt ist.
3. Dämpfungsventil (18) nach Anspruch 1 oder 2, wobei
die Ventilplatte (25; 30; 31) eine ringförmige Tellerfeder (25; 30; 31) aufweist.
4. Dämpfungsventil (18) nach Anspruch 3, wobei
die Tellerfeder (30; 31) in einem entlasteten Zustand eine konisch verjüngte Form
aufweist.
5. Dämpfungsventil (18) nach Anspruch 3 oder 4, des Weiteren mit:
einem Halteelement (22) zum Halten der Tellerfeder (25; 30; 31), so dass die Tellerfeder
(25; 30; 31) entlang der vorbestimmten Achse (23e) bewegbar ist,
wobei das Druckelement (24) die Tellerfeder (25; 30; 31) in Richtung des Ventilsitzes
(26; 26A; 26B) durch das Halteelement (22) drückt.
6. Dämpfungsventil (18) nach Anspruch 5, wobei
wenn eine Menge von von der Öffnung (23b) des Verbindungswegs (23a) zurückgekehrten
Hydrauliköls nicht weniger als eine vorbestimmte Menge ist, die Ventilplatte (25;
30; 31), zusammen mit dem Halteelement (22), in eine Richtung weg von dem Ventilsitz
(26; 26A; 26B) gegen das Druckelement (24) versetzt ist.
7. Dämpfungsventil (18) nach Anspruch 5 oder 6, wobei
das Halteelement (22) eine zylindrische Form aufweist, und
der Zuführweg (F1) das Halteelement (22) durchstößt.
8. Dämpfungsventil (18) nach einem der Ansprüche 5 bis 7, wobei
das Druckelement (24) eine Schraubenfeder (24) aufweist, die um die vorbestimmte Achse
(23e) zentriert ist,
das Halteelement (22) einen Abschnitt (22a) von kleinem Durchmesser, der einen relativ
kleinen Durchmesser aufweist, und einen Abschnitt (22b) von großem Durchmesser, der
einen relativ großen Durchmesser aufweist, und
der Abschnitt (22b) von großem Durchmesser des Halteelements (22) die Schraubenfeder
(24) umgibt, um eine Ausdehnung und ein Zusammenziehen der Schraubenfeder (24) zu
führen.
9. Dämpfungsventil nach Anspruch 8, wobei
der Abschnitt (22a) von kleinem Durchmesser des Halteelements (22) in den Durchstoßweg
in dem Zuführweg (F1) eingepasst ist, um entlang der vorbestimmten Achse (23e) verschiebbar
zu sein.
10. Dämpfungsventil (18) nach Anspruch 8 oder 9, wobei
das Halteelement (22) einen Aufnahmeabschnitt (28; 28A) zum Aufnehmen der Innenkante
(25b; 30b; 31b) der Tellerfeder (25; 30; 31) aufweist, und
der Aufnahmeabschnitt (28; 28A) zwischen dem Abschnitt (22a) mit kleinem Durchmesser
und dem Abschnitt (22b) mit großem Durchmesser gebildet ist.
11. Dämpfungsventil (18) nach einem der Ansprüche 1 bis 10, wobei
das Rückschlagventil (19) in dem Durchstoßweg angeordnet ist, der die Trennwand (23)
durchstößt.
12. Hydraulische Servolenkungsvorrichtung (100) mit:
einer Hydraulikquelle (107);
einem Öltank (117);
einem hydraulischen Aktuator (106), der ein Paar von Ölkammern (106d, 106e) zum Erzeugen
einer Steuerungshilfskraft aufweist,
einem Regelungsventil (108) zum Verbinden von einer der Ölkammern (106d, 106e) in
dem Hydraulikaktuator (106) mit der Hydraulikquelle (107) und Verbinden der anderen
der Ölkammern (106d, 106e) mit dem Öltank (117) abhängig von einer Steuerungsrichtung,
einem Paar von Verbindungswegen (115, 116) zum Verbinden des Paars von Ölkammern (106d,
106e) in dem Hydraulikaktuator (106) entsprechend mit einem Paar von Anschlüssen (108d;
108e) in dem Regelungsventil (108); und
einem Paar von Dämpfungsventilen (18), die in dem Paar von Verbindungswegen (115,
116) entsprechend vorgesehen sind, wobei jedes der Dämpfungsventile (18) ein Dämpfungsventil
(18) nach einem der Ansprüche 1 bis 11 ist.
13. Hydraulische Servolenkungsvorrichtung (100) nach Anspruch 12, wobei
die zweite Kammer (C2) in jedem der Dämpfungsventile (18) mit der entsprechenden Ölkammer
(106d, 106e) in dem Hydraulikaktuator (106) verbunden ist, und
die erste Kammer (C1) in jedem der Dämpfungsventile (18) mit dem entsprechenden Verbindungsweg
(115, 116) verbunden ist.
14. Dämpfungsventil nach Anspruch 1, wobei ein Halteelement (25) einen Abschnitt (22a)
von kleinem Durchmesser und einen Abschnitt (22b) von großem Durchmesser aufweist,
wobei eine gestufte Endfläche zwischen dem Abschnitt von kleinem Durchmesser (22a)
und dem Abschnitt von großem Durchmesser (22b) gebildet ist, und
wobei ein Aufnahmeabschnitt (28) zum Aufnehmen der Innenkante (25b) der Ventilplatte
(25) in einem in radialer Richtung inneren Teil der Endfläche vorgesehen ist, und
wobei ein Entlastungsabschnitt (22c) in einem in radialer Richtung äußeren Teil der
Endfläche vorgesehen ist, um der Ventilplatte (25) zu ermöglichen, elastisch deformiert
zu werden.
1. Soupape d'amortissement (18) comportant :
un boîtier (21) ayant une première chambre (C1), une deuxième chambre (C2), et une
cloison de séparation (23) destinée à séparer la première chambre (C1) et la deuxième
chambre (C2) l'une de l'autre ;
un passage d'alimentation (F1) destiné à délivrer de l'huile hydraulique dans la première
chambre (C1) à la deuxième chambre (C2) ;
un passage de retour (F2) destiné à renvoyer l'huile hydraulique dans la deuxième
chambre (C2) vers la première chambre (C1) ;
un clapet anti-retour (19) prévu dans le passage d'alimentation (F1) afin de réguler
la circulation de l'huile hydraulique de la deuxième chambre (C2) vers la première
chambre (C1) ;
un siège de soupape (26 ; 26A ; 26B) prévu sur la cloison de séparation (23) et face
à la première chambre (C1) ;
une plaque de soupape annulaire (25 ; 30 ; 31), qui est élastiquement déformable,
reçue dans la première chambre (C1) et opposé au siège de soupape (26 ; 26A ; 26B)
; et
un élément de poussée (24) destiné à pousser élastiquement une partie prédéterminée
(25b ; 30b ; 31b) de la plaque de soupape (25 ; 30 ; 31) vers le siège de soupape
(26 ; 26A ; 26B),
le passage d'alimentation (F1) comportant un passage de pénétration (23c) qui pénètre
dans la cloison de séparation (23) le long d'un axe prédéterminé (23e),
le passage de retour (F2) comportant un passage de communication (23a) qui fait communiquer
la première chambre (C1) et la deuxième chambre (C2) l'une avec l'autre en pénétrant
dans la cloison de séparation (23),
le passage de communication (23a) ayant une ouverture (23b) formée sur le siège de
soupape (26 ; 26A ; 26B), et
le siège de soupape (26 ; 26A ; 26B) ou bien la plaque de soupape (25 ; 30 ; 31) étant
formé avec une forme conique centrée sur l'axe prédéterminé (23e) et la plaque de
soupape (25) produisant une force de rappel élastique de façon à obtenir un équilibre
entre la force de poussée procurée par l'élément de poussée (24) et une force de réaction
par la plaque de soupape (25), la plaque de soupape (25 ; 30 ; 31) étant en contact
linéaire avec le siège de soupape (26 ; 26A ; 26B) lors du maintien de l'équilibre
entre la force de poussée élastique procurée par l'élément de poussée (24) et la force
de réaction élastique, de telle sorte que, quand un bord extérieur (25a ; 30a ; 31a)
ou bien un bord intérieur (25b ; 30b ; 31b) de la plaque de soupape (25 ; 30 ; 31)
est en butée contre le siège de soupape (26 ; 26A ; 26B), une chambre d'huile annulaire
(70) est formée entre le siège de soupape (26 ; 26A ; 26B) et la plaque de soupape
(25 ; 30 ; 31) et l'ouverture (23b) du passage de communication (23a) communique avec
la chambre d'huile annulaire (70).
2. Soupape d'amortissement (18) selon la revendication 1, dans laquelle, quand le bord
extérieur (25a ; 30a ; 31a) ou bien le bord intérieur (25b ; 30b ; 31b) de la plaque
de soupape (25 ; 30 ; 31) est en butée contre le siège de soupape (26 ; 26A ; 26B),
l'autre bord est séparé du siège de soupape (26 ; 26A ; 26B).
3. Soupape d'amortissement (18) selon la revendication 1 ou 2, dans laquelle la plaque
de soupape (25 ; 30 ; 31) comporte un ressort en forme de disque annulaire (25 ; 30
; 31).
4. Soupape d'amortissement (18) selon la revendication 3, dans laquelle le ressort en
forme de disque (30 ; 31) a une forme conique dans un état non chargé.
5. Soupape d'amortissement (18) selon la revendication 3 ou 4, comportant en outre
un élément de maintien (22) destiné à maintenir le ressort en forme de disque (25
; 30 ; 31) de telle sorte que le ressort en forme de disque (25 ; 30 ; 31) est mobile
le long de l'axe prédéterminé (23e),
l'élément de poussée (24) poussant le ressort en forme de disque (25 ; 30 ; 31) vers
le siège de soupape (26 ; 26A ; 26B) par l'intermédiaire de l'élément de maintien
(22).
6. Soupape d'amortissement (18) selon la revendication 5, dans laquelle, quand une quantité
d'huile hydraulique retournée par l'ouverture (23b) du passage de communication (23a)
n'est pas inférieure à une quantité prédéterminée, la plaque de soupape (25 ; 30 ;
31), avec l'élément de maintien (22), est déplacée dans une direction à l'écart du
siège de soupape (26 ; 26A ; 26B) contre l'élément de poussée (24).
7. Soupape d'amortissement (18) selon la revendication 5 ou 6, dans laquelle l'élément
de maintien (22) a une forme cylindrique, et le passage d'alimentation (F1) pénètre
dans l'élément de maintien (22).
8. Soupape d'amortissement (18) selon l'une quelconque des revendications précédentes
5 à 7, dans laquelle
l'élément de poussée (24) comporte un ressort hélicoïdal (24) concentré sur l'axe
prédéterminé (23e),
l'élément de maintien (22) comporte une section de faible diamètre (22a) ayant un
relativement faible diamètre et une section de grand diamètre (22b) ayant un diamètre
relativement grand, et
la section à large diamètre (22b) de l'élément de maintien (22) entoure le ressort
hélicoïdal (24), afin de guider l'expansion et la contraction du ressort hélicoïdal
(24).
9. Soupape d'amortissement selon la revendication 8, dans laquelle la section de faible
diamètre (22a) de l'élément de maintien (22) est montée dans le passage de pénétration
dans le passage d'alimentation (F1) de façon à pouvoir coulisser le long de l'axe
prédéterminé (23e).
10. Soupape d'amortissement (18) selon la revendication 8 ou 9, dans laquelle
l'élément de maintien (22) comporte une section de réception (28 ; 28A) destinée à
recevoir le bord intérieur (25b ; 30b ; 31b) du ressort en forme de disque (25 ; 30
; 31), et
la section de réception (28 ; 28A) est formée entre la section de faible diamètre
(22a) et la section de grand diamètre (22b).
11. Soupape d'amortissement (18) selon l'une quelconque des revendications 1 à 10, dans
laquelle le clapet anti-retour (19) est prévu dans le passage de pénétration qui pénètre
dans la cloison de séparation (23).
12. Direction à assistance hydraulique (100) comportant :
une source hydraulique (107) ;
un réservoir d'huile (117) ;
un dispositif d'actionnement hydraulique (106) ayant une paire de chambres d'huile
(106d, 106e) afin de produire une force d'assistance de direction ;
une soupape de commande (108) destinée à relier l'une des chambres d'huile (106d,
106e) dans le dispositif d'actionnement hydraulique (106) à la source hydraulique
(107) et à relier l'autre chambre d'huile (106d, 106e) au réservoir d'huile (117)
en fonction d'une direction de braquage,
une paire de passages de raccordement (115, 116) destinés à relier la paire de chambres
d'huile (106d, 106e) dans le dispositif d'actionnement hydraulique (106) à une paire
d'orifices (108d, 108e) dans la soupape de commande (108) respectivement ; et
une paire de soupapes d'amortissement (18) prévue dans la paire de passages de raccordement
(115, 116) respectivement, chacune des soupapes d'amortissement (18) étant une soupape
d'amortissement (18) selon l'une quelconque des revendications 1 à 11.
13. Direction à assistance hydraulique (100) selon la revendication 12, dans laquelle
la deuxième chambre (C2) dans chacune des soupapes d'amortissement (18) est reliée
à la chambre d'huile correspondante (106d, 106e) dans le dispositif d'actionnement
hydraulique (106), et
la première chambre (Cl) dans chacune des soupapes d'amortissement (18) est reliée
au passage de raccordement correspondant (115, 116).
14. Soupape d'amortissement selon la revendication 1, dans laquelle un élément de maintien
(25) comprend une section de faible diamètre (22a) et une section de grand diamètre
(22b),
une surface d'extrémité étagée étant formée entre la section de faible diamètre (22a)
et la section de grand diamètre (22b), et
une section de réception (28) destinée à recevoir le bord intérieur (25b) de la plaque
de soupape (25) étant prévue dans une partie intérieure dans la direction radiale
de la surface d'extrémité, et une section de dégagement (22c) destinée à permettre
à la plaque de soupape (25) d'être déformée élastiquement étant prévue dans une partie
extérieur dans la direction radiale de la surface d'extrémité.